Retrieving symbol graphics with SymbolLibrary SCL API does not work.

Using CurrentThread instead of AWTThread fixes the problem.

refs #1252

bundles/org.simantics.diagram/src/org/simantics/diagram/scl/SymbolLibrary.java

@@ -36,6 +36,7 @@ import org.simantics.g2d.tooltip.TooltipParticipant;
 import org.simantics.scenegraph.g2d.events.command.CommandKeyBinding;
 import org.simantics.utils.datastructures.hints.IHintContext;
 import org.simantics.utils.threads.AWTThread;
+import org.simantics.utils.threads.CurrentThread;
 import org.simantics.utils.threads.IThreadWorkQueue;
 
 public class SymbolLibrary {
@@ -48,23 +49,23 @@ public class SymbolLibrary {
 		IDiagram diagram =  Diagram.spawnNew(DiagramClass.DEFAULT);
         diagram.setHint(FlowLayout.HGAP, 5.0);
         diagram.setHint(FlowLayout.VGAP, 5.0);
-        IThreadWorkQueue thread = AWTThread.getThreadAccess();
+        // Note: Current thread seems to work with simupedia. Thus we do not need work thread system as with o.s.modeling.SCLScenegraph.
+        IThreadWorkQueue thread = CurrentThread.getThreadAccess(); //AWTThread.getThreadAccess();
         CanvasContext ctx = new CanvasContext(thread);
         initializeCanvasContext(ctx,selection);
         IHintContext hintCtx = ctx.getDefaultHintContext();
-        hintCtx.setHint(DiagramHints.KEY_DIAGRAM, diagram);
         
         ElementClass ec = item.getElementClass(diagram);
         StaticSymbol ss = ec.getSingleItem(StaticSymbol.class);
         Image source = ss == null ? DefaultImages.UNKNOWN2.get() : ss.getImage();
-        //ImageProxy proxy = new ImageProxy(source);
         
         IElement element = Element.spawnNew(ec);
         element.setHint(ElementHints.KEY_OBJECT, item);
         element.setHint(GalleryItemSGNode.KEY_IMAGE, source);
         diagram.addElement(element);
         
-        //element.getElementClass().getSingleItem(GalleryItemSGNode.class).update(element);
+        hintCtx.setHint(DiagramHints.KEY_DIAGRAM, diagram);
+        
         
         return ctx;
 	}